Thermal processing method and thermal processing apparatus through light irradiation

ABSTRACT

A susceptor is preheated through light irradiation by a halogen lamp before the first semiconductor wafer of a lot as a processing target is transferred into a chamber. The temperature of the susceptor is measured by a radiation thermometer. A control unit is configured to control the output of the halogen lamp so that the temperature of the susceptor reaches a stable temperature based on a result of the measurement of the temperature of the susceptor by the radiation thermometer. The stable temperature of the susceptor is the temperature of the susceptor when the temperature of the susceptor is risen to a constant temperature by continuously performing light irradiation heating on a plurality of semiconductor wafers in the chamber without heating the susceptor.

BACKGROUND OF THE INVENTION

Field of the Invention

The present invention relates to a thermal processing method and thermalprocessing apparatus of heating a thin-plate fine electronic substrate(hereinafter simply referred to as a “substrate”) such as asemiconductor wafer to which impurities are introduced, by irradiatingthe substrate with light.

Description of the Background Art

In a process of manufacturing a semiconductor device, impurityintroduction is a process necessary for forming a p-n junction in asemiconductor wafer. Currently, a typical impurity introduction isachieved by an ion implantation technique and a subsequent annealingtechnique. The ion implantation technique is a technology in whichimpurity elements such as boron (B), arsenic (As), and phosphorus (P)are ionized to collide onto a semiconductor wafer with a highacceleration voltage and physically perform impurity implantation.Implanted impurities are activated through anneal processing. In thisprocess, an annealing time of several seconds or longer allows theimplanted impurities to deeply diffuse by heat to have a junction depthmuch larger than required, potentially causing difficulties in favorabledevice formation.

For this reason, flash lamp annealing (FLA) has attracted attentionrecently as an anneal technology of heating a semiconductor wafer in anextremely short time. The flash lamp annealing is a thermal processingtechnology of rising temperature only at the surface of a semiconductorwafer in which impurities are implanted, in an extremely short time(several milliseconds or less) by irradiating the surface of thesemiconductor wafer with flash light using a xenon flash lamp(hereinafter, a simple notation of “flash lamp” means the xenon flashlamp).

The xenon flash lamp has an emission spectral distribution ranging fromultraviolet to near-infrared, and has a wavelength shorter than that ofthe conventional halogen lamp, which is substantially the same as thefundamental absorption band of a silicon semiconductor wafer. Thus, whenthe semiconductor wafer is irradiated with flash light from the xenonflash lamp, less light is transmitted and thus the temperature of thesemiconductor wafer can be rapidly risen. It has been found that theflash light irradiation in an extremely short time less than severalmilliseconds can selectively rise temperature only at the vicinity ofthe surface of the semiconductor wafer. Thus, when the xenon flash lampis used to rise temperature in an extremely short time, only impurityactivation can be executed without diffusing impurities deeply.

U.S. Pat. No. 4,649,261 and US2003/0183612 each disclose a thermalprocessing apparatus employing such a xenon flash lamp, which performsdesired thermal processing through a combination of a pulsed emissionlamp such as a flash lamp provided on a front surface side of asemiconductor wafer, a continuously lighting lamp such as a halogen lampprovided on a back surface side thereof. In the thermal processingapparatus disclosed in U.S. Pat. No. 4,649,261 and US2003/0183612, thesemiconductor wafer is preheated to a certain temperature by, forexample, a halogen lamp and thereafter risen to a desired processingtemperature through pulse heating by the flash lamp.

Typically, processing, such as thermal processing, of a semiconductorwafer is performed in units of lots (a set of semiconductor wafers to beprovided with processing of identical contents under identicalconditions). In substrate processing apparatus, of which a semiconductorwafer processing is performed one by one continuously and sequentiallyon a plurality of semiconductor wafers included in a lot. In a flashlamp anneal apparatus, a plurality of semiconductor wafers included in alot are transferred into a chamber one by one and are sequentiallysubject to the thermal processing.

When a flash lamp anneal apparatus that is not operational startsprocessing of a lot, the first semiconductor wafer of the lot istransferred into a chamber substantially at room temperature and thensubject to the heating processing. At the heating processing, thesemiconductor wafer supported by a susceptor in the chamber is preheatedto a predetermined temperature and then risen to a processingtemperature by flash heating. As a result, thermal conduction occursfrom the semiconductor wafer the temperature of which has risen to thesusceptor and the like in the chamber, and the temperatures of thesusceptor and the like rise accordingly. Such an increase in thetemperatures of the susceptor and the like due to the heating processingof the semiconductor wafer continues for few semiconductor wafersfollowing the first semiconductor wafer. Eventually when the heatingprocessing is performed on approximately 10 semiconductor wafers, thetemperature of the susceptor reaches a stable temperature. In otherwords, the first semiconductor wafer of the lot is processed beingsupported by the susceptor at room temperature, whereas the tenth orlater semiconductor wafer is processed being supported by the susceptorthe temperature of which has risen to the stable temperature.

This causes such a problem that a temperature history is ununiform amonga plurality of semiconductor wafers included in the lot. In particular,since several semiconductor wafers following the first semiconductorwafer of the lot are processed being supported by the susceptor atrelatively low temperatures, a temperature reached on the surface at theflash light irradiation potentially does not reach the processingtemperature. When a semiconductor wafer supported by the susceptor atlow temperature is irradiated with flash light, wafer warpage occurs insome cases because of a temperature difference between the susceptor andthe semiconductor wafer, and as a result, the semiconductor wafer ispotentially damaged.

For these reasons, in the conventional technology, before processing ofa lot is started, a dummy wafer that is not a processing target istransferred into the chamber to be supported by the susceptor and issubject to the flash heating processing under condition identical tothat of the lot to be processed, so as to rise the temperatures of thesusceptor and the like in the chamber in advance (dummy running). Theflash heating processing is performed on about 10 dummy wafers, so that,for example, the susceptor reaches a stable temperature, and thereafter,processing of the first semiconductor wafer of the lot to be processedis started. In this manner, a uniform temperature history can beachieved for a plurality of semiconductor wafers included in the lot,and additionally, wafer warpage due to a temperature difference betweenthe susceptor and a semiconductor wafer can be prevented.

However, in such dummy running, a dummy wafer that is not a processingtarget is consumed, and it takes a considerable time to perform theflash heating processing on about 10 dummy wafers, preventing efficientoperation of the flash lamp anneal apparatus.

SUMMARY OF THE INVENTION

The present invention is intended to provide a thermal processing methodof heating a substrate by irradiating the substrate with light.

According to an aspect of the present invention, the thermal processingmethod includes the steps of: (a) transferring a substrate into achamber to place the substrate on a susceptor; (b) irradiating thesubstrate placed on the susceptor with light; (c) measuring thetemperature of the susceptor before the first substrate of a lot istransferred into the chamber; and (d) heating the susceptor based on aresult of the measurement in the step (c).

A uniform temperature history can be achieved for all substrates of thelot without dummy running.

Preferably, in the step (c), temperature is measured at a plurality ofplaces on the susceptor, and in the step (d), heating control isperformed for each region including one of the plurality of places.

This achieves an improved accuracy of heating the susceptor.

The present invention is also intended to provide a thermal processingapparatus configured to heat a substrate by irradiating the substratewith light.

According to another aspect of the present invention, the thermalprocessing apparatus includes: a chamber housing a substrate; asusceptor provided inside the chamber and configured to support when thesubstrate is placed on the susceptor; a light irradiation unitconfigured to irradiate the substrate placed on the susceptor withlight; a temperature measurement unit configured to measure thetemperature of the susceptor; and a control unit configured to controlthe light irradiation unit so that the susceptor is heated through lightirradiation by the light irradiation unit based on a result of themeasurement of the temperature of the susceptor by the temperaturemeasurement unit before the first substrate of a lot is transferred intothe chamber.

A uniform temperature history can be achieved for all substrates of thelot without dummy running.

Preferably, the temperature measurement unit includes a plurality oftemperature sensors configured to measure temperature at a plurality ofplaces on the susceptor, and the control unit controls light irradiationby the light irradiation unit for each region including one of theplurality of places.

This achieves an improved accuracy of heating the susceptor.

Therefore, it is an object of the present invention to omit dummyrunning.

These and other objects, features, aspects and advantages of the presentinvention will become more apparent from the following detaileddescription of the present invention when taken in conjunction with theaccompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a vertical sectional view illustrating the configuration of athermal processing apparatus according to the present invention;

FIG. 2 is a perspective view illustrating the entire appearance of aholding unit;

FIG. 3 is a plan view of the holding unit viewed from top;

FIG. 4 is a side view of the holding unit;

FIG. 5 is a plan view of a transfer mechanism;

FIG. 6 is a side view of the transfer mechanism;

FIG. 7 is a plan view illustrating arrangement of a plurality of halogenlamps;

FIG. 8 is a diagram illustrating a drive circuit of a flash lamp;

FIG. 9 is a diagram illustrating a correlation between the number ofprocessed semiconductor wafers and the temperature of a susceptor; and

FIG. 10 is a diagram illustrating exemplary zone control of thetemperature of the susceptor.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Preferred embodiments of the present invention will be described indetail below with reference to the accompanying drawings.

First Preferred Embodiment

FIG. 1 is a vertical sectional view illustrating the configuration of athermal processing apparatus 1 according to the present invention. Thethermal processing apparatus 1 according to the present preferredembodiment is a flash lamp annealing apparatus configured to heat asemiconductor wafer W, as a substrate, in a circular disk shape byirradiating the semiconductor wafer W with flash light. The size of thesemiconductor wafer W to be processed is not particularly limited, butis, for example, φ 300 mm or φ 450 mm. Impurities are implanted in thesemiconductor wafer W before being transferred into the thermalprocessing apparatus 1, and activation processing of the implantedimpurities is executed through heating processing by the thermalprocessing apparatus 1. In FIG. 1 and the following drawings, thedimension of each component and the number thereof are exaggerated orsimplified as necessary to facilitate understanding.

The thermal processing apparatus 1 includes a chamber 6 configured tohouse the semiconductor wafer W, a flash heating unit 5 including aplurality of built-in flash lamps FL, and a halogen heating unit 4including a plurality of built-in halogen lamps HL. The flash heatingunit 5 is provided above the chamber 6, and the halogen heating unit 4is provided below the chamber 6. The thermal processing apparatus 1 alsoincludes, inside the chamber 6, a holding unit 7 configured to hold thesemiconductor wafer W in a horizontal posture, and a transfer mechanism10 configured to transfer the semiconductor wafer W between the holdingunit 7 and the outside of the apparatus. The thermal processingapparatus 1 also includes a control unit 3 configured to execute thermalprocessing of the semiconductor wafer W by controlling operationmechanisms provided to the halogen heating unit 4, the flash heatingunit 5, and the chamber 6.

The chamber 6 is provided with a chamber window made of quartz mountedabove and below a tubular chamber side part 61. The chamber side part 61substantially has a tubular shape with openings at its upper and lowersides. The upper opening is closed by mounting an upper chamber window63 thereon, and the lower opening is closed by mounting a lower chamberwindow 64 thereon. The upper chamber window 63 constituting the ceilingof the chamber 6 is a circular disk shape member made of quartz, andfunctions as a quartz window that transmits flash light emitted from theflash heating unit 5 into the chamber 6. The lower chamber window 64constituting the floor of the chamber 6 is a circular disk shape membermade of quartz, and functions as a quartz window that transmits lightfrom the halogen heating unit 4 into the chamber 6.

A reflection ring 68 is mounted at an upper part of an inner wallsurface of the chamber side part 61, and a reflection ring 69 is mountedat a lower part thereof. The reflection rings 68 and 69 are each formedin a circular ring. The upper reflection ring 68 is mounted by beinginset from above the chamber side part 61. The lower reflection ring 69is mounted by being inset from below the chamber side part 61 andfastened by a screw (not illustrated). In other words, the reflectionrings 68 and 69 are detachably mounted on the chamber side part 61. Athermal processing space 65 is defined to be an inner space of thechamber 6, which is a space enclosed by the upper chamber window 63, thelower chamber window 64, the chamber side part 61, and the reflectionrings 68 and 69.

When the reflection rings 68 and 69 are mounted on the chamber side part61, a recess 62 is formed on an inner wall surface of the chamber 6. Inother words, the recess 62 is formed, the recess 62 being enclosed by acentral part of the inner wall surface of the chamber side part 61,where the reflection rings 68 and 69 are not mounted, a lower endsurface of the reflection ring 68, and an upper end surface of thereflection ring 69. The recess 62 is formed in a circular ring on theinner wall surface of the chamber 6 along the horizontal direction,surrounding the holding unit 7 that holds the semiconductor wafer W.

The chamber side part 61 and the reflection rings 68 and 69 are made ofa metal material (for example, stainless steel) that is excellent instrength and thermal resistance. The inner peripheral surfaces of thereflection rings 68 and 69 are mirrored by electrolytic nickel plating.

The chamber side part 61 is provided with a transfer opening (furnaceentrance) 66 through which the semiconductor wafer W is transferred intoand from the chamber 6. The transfer opening 66 can be opened and closedthrough a gate valve 185. The transfer opening 66 is communicated withthe outer peripheral surface of the recess 62. With this configuration,when the transfer opening 66 is opened by the gate valve 185, thesemiconductor wafer W can be transferred to and from the thermalprocessing space 65 through the transfer opening 66 and the recess 62.When the transfer opening 66 is closed by the gate valve 185, thethermal processing space 65 in the chamber 6 is sealed.

A gas supply hole 81 for supplying processing gas (nitrogen gas (N₂) inthe present preferred embodiment) to the thermal processing space 65 isprovided at an upper part of the inner wall of the chamber 6. The gassupply hole 81 is provided higher than the recess 62, and may beprovided to the reflection ring 68. The gas supply hole 81 iscommunicated with a gas supply pipe 83 through a buffer space 82 formedin a circular ring on the inner sidewall of the chamber 6. The gassupply pipe 83 is connected with a nitrogen gas supply source 85. Avalve 84 is inserted on the path of the gas supply pipe 83. When thevalve 84 is opened, nitrogen gas is supplied from the nitrogen gassupply source 85 to the buffer space 82. Nitrogen gas flowing into thebuffer space 82 spreads inside the buffer space 82 having a smallerfluid resistance than that of the gas supply hole 81 and is supplied tothe thermal processing space 65 through the gas supply hole 81. Theprocessing gas is not limited to nitrogen gas, but may be inert gas suchas argon (Ar) or helium (He), or reactive gas such as oxygen (O₂),hydrogen (H₂), chlorine (Cl₂), hydrogen chloride (HCl), ozone (O₃), orammonia (NH₃).

A gas exhaust hole 86 for exhausting gas in the thermal processing space65 is provided at a lower part of the inner wall of the chamber 6. Thegas exhaust hole 86 is provided lower than the recess 62, and may beprovided to the reflection ring 69. The gas exhaust hole 86 iscommunicated with a gas exhaust pipe 88 through a buffer space 87 formedin a circular ring on the inner sidewall of the chamber 6. The gasexhaust pipe 88 is connected with an exhaust unit 190. A valve 89 isinserted on the path of the gas exhaust pipe 88. When the valve 89 isopened, gas in the thermal processing space 65 is exhausted to the gasexhaust pipe 88 through the gas exhaust hole 86 and the buffer space 87.A plurality of the gas supply holes 81 and the gas exhaust holes 86 maybe provided along the circumferential direction of the chamber 6, andmay be shaped in slits. The nitrogen gas supply source 85 and theexhaust unit 190 may be mechanisms provided to the thermal processingapparatus 1 or may be utilities of a factory at which the thermalprocessing apparatus 1 is installed.

Another gas exhaust pipe 191 for exhausting gas in the thermalprocessing space 65 is connected with a leading end of the transferopening 66. The gas exhaust pipe 191 is connected with the exhaust unit190 through a valve 192. When the valve 192 is opened, gas in thechamber 6 is exhausted through the transfer opening 66.

FIG. 2 is a perspective view illustrating the entire appearance of theholding unit 7. FIG. 3 is a plan view of the holding unit 7 viewed fromtop, and FIG. 4 is a side view of the holding unit 7. The holding unit 7includes a base ring 71, a coupling member 72, and a susceptor 74. Thebase ring 71, the coupling member 72, and the susceptor 74 are made ofquartz. In other words, the entire holding unit 7 is made of quartz.

The base ring 71 is a quartz member having a circular ring shape. Thebase ring 71 is supported on the wall surface of the chamber 6 whenplaced on the bottom surface of the recess 62 (refer to FIG. 1). Aplurality (in the present preferred embodiment, four) of the couplingmembers 72 are erected on the upper surface of the circular-ring basering 71 along the circumferential direction thereof. The coupling member72 is made of quartz and adhered to the base ring 71 by welding. Theshape of the base ring 71 may be an arc, which is a circular ring withpart thereof being lacked.

The flat plate susceptor 74 is supported by the four coupling members 72provided to the base ring 71. The susceptor 74 is a flat plate membermade of quartz and substantially having a circular shape. The susceptor74 has a diameter larger than the diameter of the semiconductor wafer W.In other words, the susceptor 74 has a plane size larger than that ofthe semiconductor wafer W. A plurality (in the present preferredembodiment, five) of guide pins 76 are erected on the upper surface ofthe susceptor 74. The five guide pins 76 are provided on the peripheryof a concentric circle of the outer peripheral circle of the susceptor74. The circle on which the five guide pins 76 are arranged has adiameter slightly larger than the diameter of the semiconductor wafer W.Each guide pin 76 is also made of quartz. The guide pin 76 may befabricated from quartz ingot integrally with the susceptor 74, or may befabricated separately from the susceptor 74 and attached to thesusceptor 74 by, for example, welding.

The four coupling members 72 erected on the base ring 71 are adhered tothe lower surface of a peripheral part of the susceptor 74 by welding.In other words, the susceptor 74 and the base ring 71 are fixedlycoupled with each other through the coupling members 72, and the holdingunit 7 is an integrally formed quartz member. The base ring 71 of theholding unit 7 is supported on the wall surface of the chamber 6, andthe holding unit 7 is mounted on the chamber 6. When the holding unit 7is mounted on the chamber 6, the susceptor 74 substantially having acircular disk shape is in a horizontal posture (in which the normalthereof is aligned with the vertical direction). The semiconductor waferW transferred into the chamber 6 is placed and held in a horizontalposture on the susceptor 74 of the holding unit 7 mounted on the chamber6. The semiconductor wafer W is placed inside a circle formed by thefive guide pins 76 to prevent any positional shift in the horizontaldirection. The number of the guide pins 76 is not limited to five, butmay be any number enough to prevent the positional shift of thesemiconductor wafer W.

As illustrated in FIGS. 2 and 3, an opening 78 and a cutout 77vertically penetrating are formed in the susceptor 74. The cutout 77 isa cutout provided through which a probe leading end part of a contactthermometer 130 using a thermocouple is placed. The opening 78 isprovided to allow a radiation thermometer 120 to receive radiation light(infrared light) emitted from the lower surface of the semiconductorwafer W held by the susceptor 74. In addition, four through-holes 79through which a lift pin 12 of the transfer mechanism 10 to be describedlater is penetrated for transferring of the semiconductor wafer W aredrilled in the susceptor 74. The radiation thermometer 120 and thecontact thermometer 130 are both configured to measure the temperatureof the semiconductor wafer W, but not to measure the temperature of theholder 7 including the susceptor 74.

FIG. 5 is a plan view of the transfer mechanism 10. FIG. 6 is a sideview of the transfer mechanism 10. The transfer mechanism 10 includestwo transfer arms 11. The transfer arms 11 each have an arc shape alongthe substantially circular ring shape of the recess 62. The two liftpins 12 are erected on each transfer arm 11. Each transfer arm 11 can berotated by a horizontal movement mechanism 13. The horizontal movementmechanism 13 allows the pair of transfer arms 11 to horizontally movebetween a transfer operation position (position illustrated by a solidline in FIG. 5) at which the transfer mechanism 10 performs transfer ofthe semiconductor wafer W onto the holding unit 7, and a retractedposition (position illustrated by a dashed and double-dotted line inFIG. 5) at which the transfer arms 11 do not overlap with thesemiconductor wafer W held by the holding unit 7 in plan view. Thehorizontal movement mechanism 13 may be configured to rotateindividually the transfer arms 11 through individual motors, or may beconfigured to rotate the pair of transfer arms 11 in a cooperativemanner through one motor using a link mechanism.

The pair of transfer arms 11 are moved up and down together with thehorizontal movement mechanism 13 by an elevation mechanism 14. When theelevation mechanism 14 moves up the pair of transfer arms 11 at thetransfer operation position, a total of four of the lift pins 12 passesthrough the through-holes 79 (refer to FIGS. 2 and 3) drilled in thesusceptor 74, so that the upper ends of the lift pins 12 stick out ofthe upper surface of the susceptor 74. When the elevation mechanism 14moves down the pair of transfer arms 11 at the transfer operationposition to remove the lift pins 12 from the through-holes 79, and thehorizontal movement mechanism 13 moves the pair of transfer arms 11 toopen, the transfer arms 11 are moved to the retracted position. Theretracted position of the pair of transfer arms 11 is located directlyabove the base ring 71 of the holding unit 7. Since the base ring 71 isplaced on the bottom surface of the recess 62, the retracted position ofthe transfer arms 11 is located inside the recess 62. An exhaustmechanism (not illustrated) is provided near positions at which thedriving units (the horizontal movement mechanism 13 and the elevationmechanism 14) of the transfer mechanism 10 are provided, so as toexhaust atmosphere around the driving units of the transfer mechanism 10out of the chamber 6.

As illustrated in FIGS. 1 and 2, a radiation thermometer 27 is providedinside the chamber 6. The radiation thermometer 27 is a temperaturesensor configured to detect infrared light emitted from the susceptor 74of the holder 7 to measure the temperature of the susceptor 74. In thefirst preferred embodiment, the radiation thermometer 27 is installed ata position at which the radiation thermometer 27 can measure temperatureat a central part of the susceptor 74.

The flash heating unit 5 provided above the chamber 6 includes, inside ahousing 51, a light source including a plurality (in the presentpreferred embodiment, thirty) of the xenon flash lamps FL, and areflector 52 provided to cover above the light source. A lamp lightemission window 53 is mounted on a bottom part of the housing 51 of theflash heating unit 5. The lamp light emission window 53 constituting thefloor of the flash heating unit 5 is a plate quartz window made ofquartz. Since the flash heating unit 5 is installed above the chamber 6,the lamp light emission window 53 and the upper chamber window 63 faceto each other. The flash lamps FL irradiate the thermal processing space65 with flash light from above the chamber 6 through the lamp lightemission window 53 and the upper chamber window 63 to perform flashheating of the semiconductor wafer W.

The plurality of flash lamps FL are each a bar lamp having a longcylinder shape and are arrayed in a plane such that the longitudinaldirections of the flash lamps FL are parallel to each other along a mainsurface of the semiconductor wafer W held by the holding unit 7 (alongthe horizontal direction). The plane of the array of the flash lamps FLis a horizontal plane.

FIG. 8 is a diagram illustrating a drive circuit of each flash lamp FL.As illustrated in FIG. 8, a capacitor 93, a coil 94, the flash lamp FL,and an IGBT (insulated gate bipolar transistor) 96 are connected witheach other in series. As illustrated in FIG. 8, the control unit 3includes a pulse generator 31 and a waveform setting unit 32, and isconnected with an input unit 33. The input unit 33 may be various kindsof well-known input instruments such as a keyboard, a mouse, and a touchpanel. The waveform setting unit 32 sets the waveform of a pulse signalbased on the content of input from the input unit 33, and then the pulsegenerator 31 generates a pulse signal in accordance with the waveform.

The flash lamp FL includes a glass tube (discharge tube) 92 in whichxenon gas is encapsulated and at both end parts of which an anode and acathode are arranged, and a trigger electrode 91 additionally providedon the outer peripheral surface of the glass tube 92. The capacitor 93receives predetermined voltage applied by a power unit 95, and storestherein electric charge in accordance with the applied voltage (chargevoltage). The trigger electrode 91 can receive high voltage applied froma trigger circuit 97. A timing at which the trigger circuit 97 appliesvoltage to the trigger electrode 91 is controlled by the control unit 3.

The IGBT 96 is a bipolar transistor in which a metal oxide semiconductorfield effect transistor (MOSFET) is incorporated in a gate, and is aswitching element suitable for treating a large amount of electricalpower. The gate of the IGBT 96 receives a pulse signal applied from thepulse generator 31 of the control unit 3. The IGBT 96 becomes an ONstate when a voltage (High voltage) equal to or higher than apredetermined value is applied to the gate of the IGBT 96, and the IGBT96 becomes an OFF state when a voltage (Low voltage) lower than thepredetermined value is applied. In this manner, the drive circuitincluding the flash lamp FL is turned on and off through the IGBT 96.Connection between the flash lamp FL and the corresponding capacitor 93is turned on and off by turning on and off the IGBT 96, therebycontrolling turning on and off of current flowing through the flash lampFL.

When the IGBT 96 is turned on while the capacitor 93 is charged, andhigh voltage is applied to the end-part electrodes of the glass tube 92,no electricity flows in the glass tube 92 in a normal state since xenongas is electrically an insulator. However, when the trigger circuit 97applies high voltage to the trigger electrode 91 to break theinsulation, current instantaneously flows in the glass tube 92 throughdischarge between the end-part electrodes, and light is released throughexcitation of xenon atom or molecule.

The drive circuit as illustrated in FIG. 8 is individually provided toeach of the plurality of flash lamps FL provided to the flash heatingunit 5. In the present preferred embodiment, the thirty flash lamps FLare arrayed in a plane, and thus the thirty corresponding drive circuitsas illustrated in FIG. 8 are provided.

The reflector 52 is provided above the plurality of flash lamps FL,covering the entire flash lamps FL. A basic function of the reflector 52is to reflect, toward the thermal processing space 65, flash lightemitted from the plurality of flash lamps FL. The reflector 52 is formedas an aluminum alloy plate, and has a surface (facing to the flash lampsFL) provided with roughing fabrication by blast processing.

The halogen heating unit 4 provided below the chamber 6 includes aplurality (in the present preferred embodiment, forty) of the built-inhalogen lamps HL inside a housing 41. The halogen heating unit 4 is alight irradiator configured to heat the semiconductor wafer W byirradiating the thermal processing space 65 with light from below thechamber 6 through the lower chamber window 64 by using the plurality ofhalogen lamps HL. The halogen heating unit 4 irradiates the lowersurface of the semiconductor wafer W supported by the susceptor 74 withhalogen light through the susceptor 74 made of quartz.

FIG. 7 is a plan view illustrating arrangement of the plurality ofhalogen lamps HL. The forty halogen lamps HL are arranged separately inupper and lower parts. The twenty halogen lamps HL are arranged in theupper part closer to the holding unit 7, and the twenty halogen lamps HLare arranged in the lower part farther from the holding unit 7 than theupper part. Each halogen lamp HL is a bar lamp having a long cylindershape. In each of the upper part and the lower part, the twenty halogenlamps HL are arrayed such that the longitudinal directions of thehalogen lamps HL are parallel to each other along the main surface ofthe semiconductor wafer W held by the holding unit 7 (along thehorizontal direction). In the upper and lower parts, the plane of thearray of the halogen lamps HL is a horizontal plane.

As illustrated in FIG. 7, in the upper and lower parts, the halogenlamps HL have a higher arrange density in a region opposite to aperipheral part of the semiconductor wafer W held by the holding unit 7than in a region opposite to a central part of the semiconductor waferW. In other words, in the upper and lower parts, the halogen lamps HLhave a shorter arrange pitch in the peripheral part of the lamp arraythan in the central part thereof. With this configuration, irradiationwith a larger light quantity can be performed in the peripheral part ofthe semiconductor wafer W, in which temperature fall is likely to occurat heating through irradiation with light from the halogen heating unit4.

A lamp group of the halogen lamps HL in the upper part and a lamp groupof the halogen lamps HL in the lower part are arrayed so as to intersectwith each other in a lattice. In other words, a total of forty of thehalogen lamps HL are arranged such that the longitudinal directions ofthe twenty halogen lamps HL arranged in the upper part and thelongitudinal directions of the twenty halogen lamps HL arranged in thelower part are orthogonal to each other.

Each halogen lamp HL is a filament-type light source that energizes afilament arranged inside the glass tube to make the filamentincandescent and causes light emission. The glass tube encapsulatesinert gas such as nitrogen or argon introduced with a small amount ofhalogen element (iodine or bromine, for example). The introduction ofhalogen element allows the temperature of the filament to be set to ahigh temperature while reducing damage on the filament. Thus, thehalogen lamp HL has a long life and is capable of continuously emittinglight with a high intensity as compared to a normal filament lamp. Inother words, the halogen lamp HL is a continuously lighting lampconfigured to emit light continuously for at least one second or longer.Since the halogen lamp HL is a bar lamp, the halogen lamp HL has a longlife, and the halogen lamp HL achieves an excellent efficiency ofemission to the semiconductor wafer W held above the halogen lamp HL,when arranged in the horizontal direction. Output of the forty halogenlamps HL is individually adjustable by the control unit 3.

A reflector 43 is provided in the housing 41 of the halogen heating unit4 below the two stages of the halogen lamps HL (FIG. 1). The reflector43 reflects light emitted from the plurality of halogen lamps HL towardthe thermal processing space 65.

The control unit 3 controls the above-described various kinds ofoperation mechanisms provided to the thermal processing apparatus 1. Thecontrol unit 3 has a hardware configuration same as that of a typicalcomputer. In other words, the control unit 3 includes a CPU that is acircuit configured to perform various kinds of arithmetic processing, aROM as a read-only memory configured to store therein a basic computerprogram, a RAM as a writable memory configured to store therein variouskinds of information, and a magnetic disk configured to store thereincontrol software and data. Processing in the thermal processingapparatus 1 is proceeded by the CPU of the control unit 3 executing apredetermined processing program. As illustrated in FIG. 8, the controlunit 3 includes the pulse generator 31 and the waveform setting unit 32.As described above, the waveform setting unit 32 sets the waveform of apulse signal based on the content of input from the input unit 33, andthen the pulse generator 31 outputs a pulse signal to the gate of theIGBT 96 in accordance with the waveform.

The thermal processing apparatus 1 includes, in addition to theabove-described configuration, various cooling structures to preventexcessive rise in the temperature of the halogen heating unit 4, theflash heating unit 5, and the chamber 6 due to thermal energy generatedfrom the halogen lamps HL and the flash lamps FL at the thermalprocessing of the semiconductor wafer W. For example, a water-coolingtube (not illustrated) is provided to the wall of the chamber 6. Thehalogen heating unit 4 and the flash heating unit 5 have air coolingstructures in which gas flow is generated to release heat. Air issupplied to a gap between the upper chamber window 63 and the lamp lightemission window 53 so as to cool the flash heating unit 5 and the upperchamber window 63.

The following describes a procedure of processing the semiconductorwafer W in the thermal processing apparatus 1. The semiconductor wafer Wto be processed is a semiconductor substrate to which impurities (ions)are added by the ion implantation technique. The impurities areactivated through flash light irradiation heating processing (annealing)by the thermal processing apparatus 1. A procedure of processing by thethermal processing apparatus 1 described below proceeds as the controlunit 3 controls each operation mechanism of the thermal processingapparatus 1.

First, before heating processing on the semiconductor wafer W to beprocessed, the susceptor 74 is preheated by the forty halogen lamps HLof the halogen heating unit 4. That is, before the first semiconductorwafer W included in a lot is transferred into the chamber 6, the fortyhalogen lamps HL of the halogen heating unit 4 are turned on undercontrol of the control unit 3 to heat the susceptor 74 of the holder 7.Part of light emitted from the halogen lamps HL toward the thermalprocessing space 65 is absorbed by the susceptor 74 made of quartz, sothat the temperature of the susceptor 74 is increased accordingly.

The increasing temperature of the susceptor 74 is measured by theradiation thermometer 27. However, when the semiconductor wafer W isplaced on the susceptor 74, light emitted from the lower surface of thesemiconductor wafer W transmits through the susceptor 74 to becomedisturbance light, which makes it difficult to measure the temperatureof the susceptor 74 through the radiation thermometer 27. Thesemiconductor wafer W to be processed is not placed on the susceptor 74before being transferred into the chamber 6, which allows the radiationthermometer 27 to measure the temperature of the susceptor 74.

The temperature of the susceptor 74 measured by the radiationthermometer 27 is transmitted to the control unit 3. The control unit 3performs feedback control of the output of the halogen lamps HL so thatthe temperature of the susceptor 74 becomes a predetermined temperaturebased on a result of the measurement of the temperature of the susceptor74 by the radiation thermometer 27. The susceptor 74 is heated to 200°C. to 300° C. by the halogen lamps HL. This heating temperature will bedescribed later in detail. The control unit 3 does not start processingof the semiconductor wafer W to be processed until the temperature ofthe susceptor 74 reaches the above-described predetermined temperature.When the temperature of the susceptor 74 reaches the predeterminedtemperature, the halogen lamps HL are temporarily turned off.

When the valve 84 is opened for air supply and the valves 89 and 192 areopened for air exhaust, air supplying and discharging to and from thechamber 6 is started in parallel to the preheating of the susceptor 74.When the valve 84 is opened, nitrogen gas is supplied into the thermalprocessing space 65 through the gas supply hole 81. When the valve 89 isopened, gas in the chamber 6 is exhausted through the gas exhaust hole86. With this configuration, nitrogen gas supplied from an upper part ofthe thermal processing space 65 in the chamber 6 flows downward and isexhausted from a lower part of the thermal processing space 65.

When the valve 192 is opened, gas in the chamber 6 is exhausted throughthe transfer opening 66, atmosphere around the driving units of thetransfer mechanism 10 is exhausted by the exhaust mechanism (notillustrated). At the thermal processing of the semiconductor wafer W inthe thermal processing apparatus 1, nitrogen gas is continuouslysupplied to the thermal processing space 65, and the amount of thesupply is changed as appropriate in accordance with a processingprocess.

After the temperature of the susceptor 74 measured by the radiationthermometer 27 is risen to the predetermined temperature, the controlunit 3 starts thermal processing of the first semiconductor wafer W of alot in the thermal processing apparatus 1. At start of the processing,the gate valve 185 is opened to open the transfer opening 66, and thesemiconductor wafer W in which ions are implanted is transferred intothe thermal processing space 65 in the chamber 6 through the transferopening 66 by a transfer robot outside of the apparatus. Thesemiconductor wafer W transferred in by the transfer robot is moved to aposition directly above the holder 7 and stops there. Then, the pair oftransfer arms 11 of the transfer mechanism 10 horizontally move from theretracted position to the transfer operation position and rise, so thatthe lift pins 12 stick out of the upper surface of the susceptor 74through the through-hole 79 so as to receive the semiconductor wafer W.

After the semiconductor wafer W is placed on the lift pins 12, thetransfer robot leaves the thermal processing space 65, the transferopening 66 is closed by the gate valve 185. Then, the pair of transferarms 11 are moved down to pass the semiconductor wafer W from thetransfer mechanism 10 onto the susceptor 74 of the holder 7, so that thesemiconductor wafer W is held from below in a horizontal posture. Thesemiconductor wafer W is placed on the susceptor 74 with a front surfaceon which pattern formation is provided and impurities are implantedbeing held upward. The semiconductor wafer W is placed inside the fiveguide pins 76 on the upper surface of the susceptor 74. When moved downto below the susceptor 74, the pair of transfer arms 11 is retracted tothe retracted position, in other words, the inside of the recess 62 bythe horizontal movement mechanism 13.

When the semiconductor wafer W is held from below in a horizontalposture by the holding unit 7 made of quartz, all of the forty halogenlamps HL of the halogen heating unit 4 are turned on to start preheating(assist heating). Halogen light emitted from the halogen lamps HLtransmits through the lower chamber window 64 and the susceptor 74 madeof quartz and irradiates the back surface (main surface opposite to thefront surface) of the semiconductor wafer W. The semiconductor wafer Wis preheated by receiving the light irradiation from the halogen lampsHL, and the temperature of the semiconductor wafer W rises.

When the preheating by the halogen lamps HL is performed, thetemperature of the semiconductor wafer W is measured by the contactthermometer 130. Specifically, the contact thermometer 130 including abuilt-in thermocouple contacts with the lower surface of thesemiconductor wafer W held by the holding unit 7, through the cutout 77of the susceptor 74 to measure the rising wafer temperature. Themeasured temperature of the semiconductor wafer W is transmitted to thecontrol unit 3. The control unit 3 controls output of the halogen lampsHL while monitoring whether the temperature of the semiconductor waferW, which is risen through the light irradiation from the halogen lampsHL, reaches a predetermined preheating temperature T1. In other words,the control unit 3 performs feedback control of the output of thehalogen lamps HL based on a value measured by the contact thermometer130 so that the temperature of the semiconductor wafer W becomes equalto the preheating temperature T1. The preheating temperature T1 is 200°C. to 800° C. approximately, and preferably 350° C. to 600° C.approximately, at which diffusion of the impurities added to thesemiconductor wafer W by heat is unlikely to occur (in the presentpreferred embodiment, 600° C.). The measurement of the temperature ofthe semiconductor wafer W may be performed by the radiation thermometer120 in place of or in addition to the contact thermometer 130.

After the temperature of the semiconductor wafer W has reached thepreheating temperature T1, the control unit 3 temporarily maintains thesemiconductor wafer W at the preheating temperature T1. Specifically,when the temperature of the semiconductor wafer W measured by thecontact thermometer 130 reaches the preheating temperature T1, thecontrol unit 3 adjusts the output of the halogen lamps HL to maintainthe temperature of the semiconductor wafer W substantially at thepreheating temperature T1.

The temperature of the entire semiconductor wafer W is uniformly risento the preheating temperature T1 through the preheating by the halogenlamps HL. At the preheating by the halogen lamps HL, the temperature ofthe peripheral part of the semiconductor wafer W, from which heat ismore likely to be released, tends to fall below the temperature of thecentral part of the semiconductor wafer W. However, the arrange densityof the halogen lamps HL in the halogen heating unit 4 is higher in theregion opposite to the peripheral part of the semiconductor wafer W thanin the region opposite to the central part of the semiconductor wafer W(refer to FIG. 7). With this configuration, a larger amount of light isincident on the peripheral part of the semiconductor wafer W, from whichheat is likely to be released, thereby achieving a uniform in-planetemperature distribution of the semiconductor wafer W at the preheating.In addition, since the inner peripheral surface of the reflection ring69 mounted on the chamber side part 61 is mirrored, a larger amount oflight is reflected toward the peripheral part of the semiconductor waferW by the inner peripheral surface of the reflection ring 69, therebyfurther achieving a uniform in-plane temperature distribution of thesemiconductor wafer W at the preheating.

When a predetermined time has elapsed after the temperature of thesemiconductor wafer W reached the preheating temperature T1, the flashlamps FL of the flash heating unit 5 irradiate the surface of thesemiconductor wafer W with flash light. Electric charge is previouslyaccumulated on the capacitor 93 by the power unit 95 before theirradiation with flash light by the flash lamps FL. Then, while electriccharge is accumulated on the capacitor 93, a pulse signal is output fromthe pulse generator 31 of the control unit 3 to the IGBT 96 so as toturn on and off drive of the IGBT 96.

The waveform of the pulse signal can be defined by inputting, from theinput unit 33, a recipe in which time (ON time) of a pulse width andtime (OFF time) of a pulse interval are sequentially set as parameters.When such a recipe is input to the control unit 3 by an operator throughthe input unit 33, the waveform setting unit 32 of the control unit 3sets a pulse waveform that repeats on and off in accordance with therecipe. Then, the pulse generator 31 outputs a pulse signal inaccordance with the pulse waveform set by the waveform setting unit 32.Accordingly, the pulse signal having the set waveform is applied to thegate of the IGBT 96 to control the turning on and off of drive of theIGBT 96. Specifically, the IGBT 96 becomes the ON state when the pulsesignal input to the gate of the IGBT 96 is on, and the IGBT 96 becomesthe OFF state when the pulse signal is off.

The control unit 3 applies high voltage (trigger voltage) to the triggerelectrode 91 by controlling the trigger circuit 97 in synchronizationwith a timing at which the pulse signal output from the pulse generator31 becomes on. When the pulse signal is input to the gate of the IGBT 96while electric charge is accumulated on the capacitor 93, and highvoltage is applied to the trigger electrode 91 in synchronization withthe timing at which the pulse signal becomes on, current always flowsbetween the end-part electrodes in the glass tube 92, and light isreleased through excitation of xenon atom or molecule when the pulsesignal is on.

In this manner, the thirty flash lamps FL of the flash heating unit 5emit light to irradiate the front surface of the semiconductor wafer Wplaced on the susceptor 74 with flash light. When the flash lamps FLemit light without using the IGBT 96, however, electric chargeaccumulated on the capacitor 93 is consumed at one light emission, anoutput waveform from each flash lamp FL is a single pulse having a widthof 0.1 millisecond to 10 milliseconds approximately. In contrast,according to the present preferred embodiment, the IGBT 96 as aswitching element is connected in a circuit, and a pulse signal isoutput to the gate of the IGBT 96 to turn on and off, through the IGBT96, supply of electric charge from the capacitor 93 to the flash lampFL, thereby turning on and off current flowing through the flash lampFL. Accordingly, chopper control is performed on light emission of theflash lamp FL, so that electric charge accumulated on the capacitor 93is consumed in a divided manner, and the flash lamp FL repeats flashingin an extremely short time. Since the next pulse is applied to the gateof the IGBT 96 and the value of current increases again before the valueof current flowing through the circuit becomes completely zero, thelight emission does not have completely zero output while the flashlamps FL repeats flashing.

With this configuration, a light emission pattern of the flash lamp FLcan be freely defined by controlling, through the IGBT 96, the turningon and off of current flowing through the flash lamps FL, and thus thetime and intensity of light emission can be freely adjusted.Specifically, for example, when the ratio of the time of the pulse widthrelative to the time of the pulse interval input from the input unit 33is increased, current flowing through the flash lamp FL is increased andthus the intensity of light emission is increased. In contrast, when theratio of the time of the pulse width relative to the time of the pulseinterval input from the input unit 33 is decreased, current flowingthrough the flash lamp FL is decreased and the intensity of lightemission is decreased. The intensity of light emission of the flash lampFL is constantly maintained by appropriately adjusting the ratio of thetime of the pulse interval relative to the time of the pulse width inputfrom the input unit 33. When the total time of a combination of the timeof the pulse width and the time of the pulse interval input from theinput unit 33 is increased, current continuously flows through the flashlamp FL for a relatively longer time and the flash lamp FL has a longerlight emission time. The light emission time of the flash lamp FL is 1second or less at maximum.

When irradiated with flash light from the thirty flash lamps FL, thesemiconductor wafer W is subject to flash heating. The front surfacetemperature of the semiconductor wafer W subject to the flash heatinginstantaneously rises to a processing temperature T2 equal to or higherthan 1,000° C. to activate the impurities implanted in the semiconductorwafer W, and then the front surface temperature rapidly falls. Since theflash lamps FL emit light during the light irradiation by the halogenlamps HL, the front surface temperature of the semiconductor wafer Wfalls to the vicinity of the preheating temperature T1.

The halogen lamps HL are turned off after a predetermined time haselapsed after the flash heating processing ended. Accordingly, thetemperature of the semiconductor wafer W rapidly falls from thepreheating temperature T1. The temperature of the semiconductor wafer Wduring the fall is measured by the contact thermometer 130 or theradiation thermometer 120, and a result of the measurement istransmitted to the control unit 3. The control unit 3 monitors whetherthe temperature of the semiconductor wafer W falls to a predeterminedtemperature based on the result of the measurement. Then, after thetemperature of the semiconductor wafer W falls below the predeterminedtemperature, the pair of transfer arms 11 of the transfer mechanism 10are horizontally moved from the retracted position to the transferoperation position and risen again, so that the lift pins 12 stick outof the upper surface of the susceptor 74 to receive, from the susceptor74, the semiconductor wafer W after the thermal processing.Subsequently, the transfer opening 66 closed by the gate valve 185 isopened, the semiconductor wafer W placed on the lift pins 12 istransferred out by the transfer robot outside of the apparatus, whichcompletes the heating processing of the semiconductor wafer W in thethermal processing apparatus 1.

Typically, the processing of the semiconductor wafer W is performed inunits of lots. A lot is a set of the semiconductor wafers W to besubject to processing of identical contents under identical conditions.In the thermal processing apparatus 1 according to the present preferredembodiment, a plurality of the semiconductor wafers W included in a lotare sequentially transferred into the chamber 6 one by one to be subjectto the heating processing.

When the thermal processing apparatus 1 that has not performedprocessing for a while starts processing of a lot without performing theabove-described preheating of the susceptor 74, the first semiconductorwafer W of the lot is transferred into the chamber 6 substantially atroom temperature and subject to the flash heating processing. Examplesof such a case include a case in which the first lot is processed afterthe thermal processing apparatus 1 has been started after maintenance,and a case in which a long time has elapsed since processing of the lastlot. At the heating processing, thermal conduction occurs from thesemiconductor wafer W the temperature of which has been risen to thesusceptor 74 and the like in the chamber, the temperature of thesusceptor 74, which was initially at room temperature, is graduallyrisen by heat accumulation as the number of processed semiconductorwafers W increases.

FIG. 9 is a diagram illustrating a correlation between the number ofprocessed semiconductor wafers W and the temperature of the susceptor74. The temperature of the susceptor 74, which was at room temperaturebefore the processing starts, is gradually risen by heat transfer fromthe semiconductor wafer W as the number of processed semiconductorwafers W increases. Then, when the heating processing is performed onapproximately 10 semiconductor wafers W, the temperature of thesusceptor 74 reaches a constant stable temperature Ts. In the susceptor74, which has reached the stable temperature Ts, the amount of heattransfer from the semiconductor wafer W to the susceptor 74 is balancedwith the amount of heat discharge from the susceptor 74. The amount ofheat transfer from the semiconductor wafer W is larger than the amountof heat discharge from the susceptor 74 until the temperature of thesusceptor 74 reaches the stable temperature Ts, and thus the temperatureof the susceptor 74 is gradually risen by heat accumulation as thenumber of processed semiconductor wafers W increases. In contrast, sincethe amount of heat transfer from the semiconductor wafer W is balancedwith the amount of heat discharge from the susceptor 74 after thetemperature of the susceptor 74 has reached the stable temperature Ts,the temperature of the susceptor 74 is maintained at the constant stabletemperature Ts.

When the processing is started on the chamber 6 at room temperature asdescribed above, the semiconductor wafer W in an early part of a lot andthe semiconductor wafer W in the following part of the lot are supportedby the susceptor 74 at different temperatures, which results in anununiform temperature history. In addition to this ununiform temperaturehistory, the semiconductor wafer W in the early part is subject to theflash heating processing while being supported by the susceptor 74 atlow temperature, which causes wafer warpage in some cases. For thisreason, as described above, before the processing of the lot is started,dummy running is conventionally performed that a dummy wafer that is nota processing target is transferred into the chamber 6 and subject to thesame flash heating processing as that on the semiconductor wafer W to beprocessed so that the temperatures of the susceptor 74 and the like inthe chamber are risen to the stable temperature Ts.

In the present preferred embodiment, the susceptor 74 is preheatedthrough light irradiation by the halogen lamps HL before the firstsemiconductor wafer W of a lot is transferred into the chamber 6. Duringthe preheating, the control unit 3 controls the output of the halogenlamps HL so that the temperature of the susceptor 74 reaches theabove-described stable temperature Ts based on a result of themeasurement of the temperature of the susceptor 74 by the radiationthermometer 27. Specifically, the stable temperature Ts is obtained inadvance by, for example, experiment or simulation and stored in astorage unit of the control unit 3. Then, the light irradiation heatingof the susceptor 74 is performed while the control unit 3 controls theoutput of the halogen lamps HL so that the temperature of the susceptor74 measured by the radiation thermometer 27 reaches the stabletemperature Ts.

The stable temperature Ts is the temperature of the susceptor 74 whenthe temperature of the susceptor 74 is risen to a constant temperatureby continuously performing the light irradiation heating on a pluralityof the semiconductor wafers W of a lot in the chamber 6 withoutpreheating the susceptor 74. The stable temperature Ts differs dependingon the preheating temperature T1 of the semiconductor wafer W includedin the lot, but is in a range of 200° C. to 300° C. Then, the thermalprocessing of the first semiconductor wafer W of the lot is startedafter the temperature of the susceptor 74 has risen to the stabletemperature Ts.

Since the temperature of the susceptor 74 is risen to the stabletemperature Ts through light irradiation by the halogen lamps HL beforethe thermal processing of the first semiconductor wafer W of the lot isstarted, all semiconductor wafers W of the lot are supported by thesusceptor 74 at the same temperature, thereby achieving a uniformtemperature history. In addition, the semiconductor wafer W in the earlypart of the lot is supported by the susceptor 74 the temperature ofwhich is risen to the stable temperature Ts, thereby preventing waferwarpage due to a temperature difference between the susceptor 74 and thesemiconductor wafer W. Accordingly, the conventional dummy running, inwhich heating processing is performed on several dummy wafers, can beomitted, so that the substrate processing apparatus 1 can be efficiencyoperated.

Second Preferred Embodiment

The following describes a second preferred embodiment of the presentinvention. The entire schematic configuration of a thermal processingapparatus and a procedure of processing the semiconductor wafer Waccording to the second preferred embodiment are substantially same asthose of the first preferred embodiment, but the number of radiationthermometers configured to measure the temperature of the susceptor 74is different from the first preferred embodiments. Although the singleradiation thermometer 27 is provided to measure temperature at a centralpart of the susceptor 74 in the first preferred embodiment, a pluralityof radiation thermometers are provided to measure temperature at aplurality of places on the susceptor 74 in the second preferredembodiment.

Specifically, in the second preferred embodiment, a total of threeradiation thermometers of a radiation thermometer configured to measuretemperature at a central part of the susceptor 74, a radiationthermometer configured to measure temperature at an edge part of thesusceptor 74, and a radiation thermometer configured to measuretemperature at a middle part between the central part and the edge partof the susceptor 74 are installed. In the second preferred embodiment,the light irradiation by the halogen heating unit 4 is controlled foreach region including one of a plurality of temperature measurementplaces on the susceptor 74. In other words, zone control of thetemperature of the susceptor 74 is performed.

FIG. 10 is a diagram illustrating exemplary zone control of thetemperature of the susceptor 74. The susceptor 74 having a substantiallycircular shape is divided into three regions of a central zone CZ, amiddle zone MZ, and an edge zone EZ that are concentric circles. Theabove-described three radiation thermometers measure temperature at thecentral zone CZ, the middle zone MZ, and the edge zone EZ, respectively.Then, the control unit 3 controls the output of the halogen lamps HL sothat temperature at the central zone CZ, the middle zone MZ, and theedge zone EZ each reaches the stable temperature Ts based on a result ofthe measurement of temperature at the central zone CZ, the middle zoneMZ, and the edge zone EZ by the three radiation thermometers. The outputof the forty halogen lamps HL is individually adjustable, and thus thecontrol unit 3 can adjust the output of the halogen lamps HLcorresponding to the central zone CZ, the middle zone MZ, and the edgezone EZ. For example, when temperature at the edge zone EZ on thesusceptor 74 is lower than temperature at the central zone CZ and themiddle zone MZ, the control unit 3 increases the output of the halogenlamps HL (the halogen lamps HL positioned below the edge zone EZ)corresponding to the edge zone EZ so as to increase the quantity oflight incident on the edge zone EZ. Accordingly, the edge zone EZ on thesusceptor 74 is heated intensively to have the same temperature as thatat the central zone CZ and the middle zone MZ, so that the entiresusceptor 74 is uniformly heated to the stable temperature Ts.

The second preferred embodiment has the same configuration as that ofthe first preferred embodiment except for the zone control of thetemperature of the susceptor 74 through a plurality of radiationthermometers. In the second preferred embodiment, the temperature of thesusceptor 74 is risen to the stable temperature Ts through lightirradiation by the halogen lamps HL before the thermal processing of thefirst semiconductor wafer W of a lot is started, and thus allsemiconductor wafers W of the lot are supported by the susceptor 74 atthe same temperature, thereby achieving a uniform temperature history.In addition, the semiconductor wafer W in an early part of a lot issupported by the susceptor 74 the temperature of which has risen to thestable temperature Ts, thereby preventing wafer warpage due to atemperature difference between the susceptor 74 and the semiconductorwafer W. Accordingly, the conventional dummy running, in which heatingprocessing is performed on several dummy wafers, can be omitted, so thatthe substrate processing apparatus 1 can be efficiency operated. Inaddition, in the second preferred embodiment, since the zone control ofthe temperature of the susceptor 74 is performed through a plurality ofradiation thermometers, the temperature of the susceptor 74 can be risenaccurately and uniformly.

<Modification>

The above describes the preferred embodiments of the present invention,but various kinds of modifications of the present invention other thanthose described above can be performed without departing from the scopeof the present invention. For example, in the above-described preferredembodiments, the susceptor 74 is heated by the halogen lamps HL forpreheating the semiconductor wafer W, but the present invention is notlimited thereto, and the susceptor 74 made of quartz may be heated by adedicated heating mechanism such as a resistive heater.

In the above-described preferred embodiments, the temperature of thesusceptor 74 is measured by a radiation thermometer, but may be measuredby a contact thermometer including a thermocouple.

The temperature of the susceptor 74 does not necessarily need to beaccurately measured because it is difficult to accurately measure thetemperature of the susceptor 74 made of quartz through the radiationthermometer 27. Specifically, since it is sufficient to only know thatthe temperature of the susceptor 74 reaches the stable temperature Ts,the control unit 3 may perform relative comparison between thetemperature of the susceptor 74 measured by the radiation thermometer 27and the stable temperature Ts, when controlling the output of thehalogen lamps HL so that the temperature difference becomes zero. Inthis case, however, the stable temperature Ts needs to be measured bythe same radiation thermometer 27 through experiment in advance.Moreover, the control unit 3 may control the output of the halogen lampsHL so that the output of the radiation thermometer 27 when the stabletemperature Ts is measured is equal to the output of the radiationthermometer 27 when the temperature of the susceptor 74 to be preheatedis measured.

In the second preferred embodiment, the three radiation thermometers areprovided and the susceptor 74 is divided into the three zones to performthe zone control, but the present invention is not limited thereto. Twoor more of temperature sensors may be provided to perform heatingcontrol for each region including one of a plurality of temperaturemeasurement places.

In the second preferred embodiment, the heating control is performed toachieve the same temperature at all zones of the susceptor 74, but maybe performed to achieve different temperatures in the respective zonesof the susceptor 74 depending on a processing purpose. For example, inorder to prevent relative temperature reduction in a peripheral part ofthe semiconductor wafer W at preheating, the output of the halogen lampsHL may be controlled so that temperature at the edge zone EZ on thesusceptor 74 is higher than temperature at the central zone CZ and themiddle zone MZ.

In the above-described preferred embodiments, the light emission of theflash lamps FL is controlled by the IGBT 96, but the IGBT 96 is notnecessarily an essential element. When the flash lamps FL are configuredto emit light without using the IGBT 96, the same effect as those of theabove-described preferred embodiments can be obtained through theconfiguration that the temperature of the susceptor 74 is risen to thestable temperature Ts before the thermal processing of the firstsemiconductor wafer W of a lot is started.

Although the thirty flash lamps FL are provided to the flash heatingunit 5 in each of the above-described preferred embodiments, the presentinvention is not limited thereto, and an optional number of the flashlamps FL may be provided. Each flash lamp FL is not limited to a xenonflash lamp, but may be a krypton flash lamp. The number of the halogenlamps HL included in the halogen heating unit 4 is not limited to forty,but may be optional as long as a plurality of halogen lamps are arrangedin upper and lower parts.

A substrate to be processed by the thermal processing apparatusaccording to the present invention is not limited to a semiconductorwafer, but may be a glass substrate used for a flat panel display suchas a liquid crystal display device or a substrate for a solar battery.The technology according to the present invention is also applicable tothermal processing of a high-dielectric-constant gate insulating film(high-k film), bonding of metal and silicon, and crystallization ofpolysilicon.

While the invention has been shown and described in detail, theforegoing description is in all aspects illustrative and notrestrictive. It is therefore understood that numerous modifications andvariations can be devised without departing from the scope of theinvention.

What is claimed is:
 1. A thermal processing method of heating asubstrate by irradiating the substrate with light, the method comprisingthe steps of: (a) transferring a substrate into a chamber to place thesubstrate on a susceptor; (b) irradiating the substrate placed on saidsusceptor with light; (c) measuring the temperature of said susceptorbefore the first substrate of a lot is transferred into said chamber;and (d) heating said susceptor based on a result of the measurement insaid step (c), wherein when a stable temperature is set as thetemperature of said susceptor when the temperature of said susceptor hasrisen to a constant temperature by continuously irradiating a pluralityof substrates of a lot, with light to heat the substrates withoutheating said susceptor, in said step (d), said susceptor is heated sothat the temperature of said susceptor reaches said stable temperature.2. The thermal processing method according to claim 1, wherein in saidstep (c), temperature is measured at a plurality of places on saidsusceptor, and in said step (d), heating control is performed for eachregion including one of said plurality of places.
 3. The thermalprocessing method according to claim 1, wherein, in said step (b), saidsubstrate is irradiated by a flash lamp with flash light from one sideof said chamber.
 4. The thermal processing method according to claim 3,wherein in said step (b), said substrate is further irradiated by ahalogen lamp with light from the other side of said chamber, and in saidstep (d), said susceptor is heated through light irradiation by saidhalogen lamp.